Apparatus and method for providing graphical configurations by sequentially directing a radiant energy beam to present image positions

ABSTRACT

A phototypesetting system employs a cathode-ray tube to present characters of typesetting quality wherein each of the characters displayed is generated by directing the cathode-ray tube beam to a series of locations, each immediately adjacent its previous location, where the beam is energized for a predetermined period of time. A character memory, such as an optically encoded disc, supplies digital information to electronic circuitry which initially locates the beam within a character field and then directs the beam sequentially to additional locations, each of the locations immediately adjacent the previous location, thus forming characters from a series of illuminated spots. Additional deflection signals are supplied to control the cathode-ray tube to move the beam automatically to the next character position after each character has been formed in preparation for the writing of subsequent characters.

United States Patent Inventors Edwin R. Kolb University Heights; RobertM. Horvath, Parrna, both of, Ohio 110,349 Mar. 4, 1968 May 25, 1971Appl. No. Filed Patented Assignee Cleveland, Ohio Harris-IntertypeCorporation APPARATUS AND METHOD FOR PROVIDING GRAPHICAL CONFIGURATIONSBY SEQUENTIALLY DIRECTING A RADIANT ENERGY BEAM TO PRESENT IMAGEPOSITIONS Primary Examiner.lohn W. Caldwell Assistant Examiner-David L.Trafton Attorney-Yount & Tarolli ABSTRACT: A phototypesetting systememploys a cathoderay tube to present characters of typesetting qualitywherein each of the characters displayed is generated by directing thecathode-ray tube beam to a series of locations, each immediatelyadjacent its previous location, where the beam is energized for apredetermined period of time. A character memory, such as an opticallyencoded disc, supplies digital information to electronic circuitry whichinitially locates the beam within a character field and then directs thebeam sequentially to additional locations,'each of the locationsimmediately adjacent the previous location, thus forming characters froma series of illuminated spots. Additional deflection signals aresupplied to control the cathode-ray tube to move the beam automaticallyto the next character position after each character has been formed inpreparation for the writing of subsequent characters.

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sum 15 HF 17 FIG-11B L lo LD 1oo'-s 2oo-s soous DELAY LINE \82 4oo-sTOTAQ. DELAY soon APPARATUS AND METHOD FOR PROVIDINGGRAPHICAL-CONFIGURATIONS BY SEQUENTIALLY DIRECTING A RADIANT ENERGY BEAMTO PRESENT IMAGE POSITIONS RELATED APPLICATIONS Reference is hereby madeto U.S. Pat. application Ser. No. 59l,734, filed Nov. 3, 1966, entitledTYPESE'I'IING SYSTEM; Ser. No. 608,l6l, filed Jan. 9, 1967, entitled EN-CODER READ OUT APPARATUS; and Ser. No. 805,l05, filed concurrentlyherewith entitled CHARACTER MEMORY.

BACKGROUN D OF TH E INVENTION High speed phototypesetting devices usingcathode-ray tubes are commonly employed to display charactersforsubsequent recordation on photographic film. Different types ofcharacter generators have been used to form these characters, suchgenerators including character grids used inconjunction with a scanningvideo tube, or core matrix or magnetic drum memories which are used togenerate the characters by scanning the character field in a raster scanpattern either by forming the characters from a series of lines with thecathoderay tube beam being energized only in those areas where thecharacter is present, or by turning the beam off and on as it is movedin a series of incremental steps in the raster pattern.

One disadvantage of the raster scan type of character generating systemslies in the fact that valuable time is being wasted while the beamcontrol circuitry attempt to direct the beam to areas which form no partof the character, and where the beam therefore remains deenergized.

This invention relates to an improved typesetting apparatus wherein thecharacters may be fonned by moving a beam of energy, such as theelectron beam of a cathode-ray tube, to a plurality of discretelocations in a predetermined sequence and energizing he beam of energyat each of those locations for a predetermined'period of time. The beamis therefore never directed to an area which forms no part of thecharacter, with the result that the character is generated in a minimumof time.

Each of the characters in a font of type is represented by digitalinformation recorded in character memory means,

such as an optical character memory adapted to be rotated at arelatively high rate of speed. The digital character information isrecorded as a series of bytes, each consisting of three bits, each byteforming an instruction to cause the beam to move to one of the locationsimmediately adjacent its previous location. The character is thereforeformed by focusing a beam of energy onto the energy responsive surfaceof the tube and moving the beam to a plurality of predeterminedlocations by modifying the output of a circuit which controls thevertical and horizontal location of cathode ray tube beam in discreteincrements. Although a three-bit code is used to move the beam to a newlocation and expose the film, as opposed to the single digit code usedto control the intensity of the beam in those character generatorswherein the characters are formed by scanninga portion of thecathode-ray tube face in a raster ,pattern, it has been found that thetime for character generation is nevertheless reduced since the beam isnever directed to a location which does not form part of the character.

A group of codes are associated with each character track on the opticalcharacter memory to supply control information to the electroniccircuitry used in the formation of the characters. For example, it hasbeen found that more rapid access to the character information may beaccomplished by dividing each character into a plurality of sections,and supplying each of those sections with a code identifying thestarting coordinates of that section with respect to the remainder ofthe character. A more complete explanation of this type of charactergeneration may be found in the above mentioned .copending US. Pat.application, Ser. No. 805,l05. Also, the

number of sections required to form a complete character may be includedas part of the control information, thus providing for flexibility inthe generation of the character.

The control information may also include codes indicating the normalizedwidth of the character, which, when multiplied with the actualhorizontal point size of the character being displayed, will give asignal which will cause the beam of energy to be moved to the properhorizontal location after the formation of that character is completed.Still another portion of the control data may indicate the point size ofthe recorded character which, when multiplied with the vertical anhorizontal point size, will produce signals controlling the size of thecharacter formed as well as the time during which the beam is energizedin each location.

Accordingly, objects of this invention are to provide an improved methodand apparatus for generating characters of typesetting quality byenergizing a beam of energy to form a spot and positioningthe spot at aplurality of predetermined, immediately adjacent locations within acharacter field in information from a character memory, each of thelocations forming the character being identified by reference to itsimmediately preceding location, without directing the beam into areaswhich form no part of the character; to provide a method and apparatusfor generating characters of typesetting quality wherein the charactersare formed from a plurality of spots, the spacing between spots beingconsistent within a character, and the spot size relative to the totalsize of the character being predetermined to produce characters of highresolution; to provide a method and apparatus for forming characters oftypesetting quality wherein the digital information representing acharacter is stored on a cyclically moving memory, and wherein rapidaccess to the character information is provided by dividing eachcharacter into a number of sections with the location of each sectionwithin the character field being so identified that a complete charactermaybe formed from any sequence of sections which make up a completecharacter, and with the generation of each section being accomplished bymoving the beam sequentially to a series of predetermined locationsfirst with reference to the starting location of that section andafterwards with reference to the previous location of the beam; and toprovide a typesetting methodand apparatus wherein characters may bedisplayed an area at a time, with the intercharacter spacing beingautomatically provided in response in a stepwise manner to the size ofthe character actually formed as indicated by the point size of thecharacter stored in the character memory and selected by a controlrecord. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a diagrammatic viewof a system for generating characters of typesetting quality on the faceof a cathode-ray tube with a part of the system shown as electricalblock diagrams;

FIG. 2 represents a character memory and illustrates the recordedinformation representing a character being repeated about the charactermemory with each repetition being divided into a number of sections;

FIG. 3 is an enlarge view of a portion of the character memory discshown in FIG. 2, with two clock tracks and a single discrete charactertrack being shown;

FIG. 4 is a diagram showing the direction in which the cathode-ray-tube.beam moves in accordance with the numerical instructions derived fromthe character memory;

FIG. 5 is an enlarged view of the letter a made up of several numbers,each number representing an instruction for moving the cathode-ray tubebeam to a location immediately adjacent its present location to form thecharacter;

FIG. 6 is an enlarged view of a portion of the letter a shown in FIG. 5showing how the cathode-ray tube beam is moved in response to specificinstructions from the character memory counter, the distribution gates,the skip counter and the section counter;

FIGS. A through 10D are detailed logic diagrams showing the controllogic of the character generator of his invention;

FIGS. 11A and 11B are detailed logic diagrams of the clock used tocontrol the character generator of this invention in response to clocksignals from the character memory;

FIGS. 12A and 12B are detailed logic diagrams showing the x and yup-down counters, the PREDlPS register and the normalized widthregister.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring now to FlG.'l whichshows in part a block dia gram of a device for generating characters oftypesetting quality on a cathode-ray tube, the character storage memoryis shown schematically at 10 and is formed from a transparent dischaving alphanumeric characters optically stored thereon as a pluralityof digital bytes which may be presented in a sequential manner. Thecharacter storage memory may be similar in its construction andarrangement of tracks containing character information to that characterstorage memory shown and described in copending US. Pat. applicationSer. No. 608,l6l, filed Jan. 9, 1967, and assigned to the same assigneeas the present invention. In that copending application,

an optically transparent character storage memory is.

described as containing six bands, with each of the bands con taining 35discrete tracks having optical marks permanently recorded thereon.

While a singlediscrete track is herein described as containing theinformation for a single character in serial form, it is, understoodthat a plurality of tracks, usually adjacent, may also be used torepresent in parallel form the information required for the generationof a single character. In either case, the information for charactergeneration will be regarded as being contained in a single discretetrack in this application. It is also understood that a plurality ofcharacter storage memories may be provided and that a pickup device isassociated with each of the bands on each of the character memories.Either mechanical or electronic switching may be employed to select thecharacter storage memory to be used and the particular band within theselected memory.

The digital information contained within the tracks on the charactermemory 10 is illuminated by a light source 11 and the image of aplurality of these tracks is projected onto a fiber optic pickupassembly 12 where that image is optically magnified and focused ontoindividual fiber optic bundles l3 and transmitted by means of thesebundles 13 to photomultiplier tubes 15, one photomultiplier tube foreach of the tracks within a band. The character memory 10 is rotated bymeans of a motor 16 to cause relative movement between the charactermemory 10 and the pickup means 12.

In the embodiment described herein, two of the photomultiplier tubes areused to sense the timing tracks contained on the character memory 10 andgenerate electrical pulses which are thereafter used to provide thetiming or clock signals for the remainder of the character generatingapparatus, as will be described in detail hereinafter. The remainder ofthe photomultiplier tubes sense the digital information contained incorresponding tracks on the character memory 10, and the electricalsignals produced thereby are used to control the position of a beam ofenergy, such as the electron beam in a cathode-ray tube, to form acharacter by moving the beam to a plurality of predetermined locationswithin a character field. Appropriate switching circuitry is provided toselect the photomultiplier output to direct this character generatingfunction in response to external commands.

The electrical output of each photomultiplier tube 15 is applied to acharacter generator circuit 20, the function of which is to sense thedigital information contained within a selected one of the charactertracks and convert that information into control signals, hereinafterdescribed as character generating signals, which are then applied to thevertical and horizontal deflection amplifier circuits 21 and 22 for thecathode-ray tube 25. The character generator circuit 20 also controlsthe energization of the cathode-ray tube beam generating means andenergizes the beam only in those areas which form a part of thecharacter to be displayed.

A control record, such as a magnetic tape 27, passes through a tapereader 28 where it is read and the electrical output fed into a buffer30. Of course, other types of control means, such as the output of acomputer or paper tape, may be used in supplying the control signals tothe buffer 30. The control record 27 contains information relating to,but not limited to, character selection, intercharacter and interwordspaces, and leading instructions when the system is used as aphototypesetter.

The buffer 30 accepts information from the control record at its optimumread out rate, and then transfers that information to the decodercircuit 31 at a rate which can be accepted by the phototypesettingsystem. Different control functions will take differing amounts of time,and even the generation of certain characters will take longer than thegeneration of other characters. The output of the decoder 31 is appliedto the control circuit 35 which in turn supplies the characterpositioning signal to the horizontal and vertical circuits 21 and 22 forpositioning the electron beam of the cathode-ray tube, and thus theentire character, prior to the generation of each character. Selectionamong the characters within a band on the character memory 10 isdetermined by another output from the decoder 31 to the characterselection circuit 36.

In the preferred embodiment of this invention, the cathoderay tubedisplaying the characters uses electromagnetic deflection means, andboth the character positioning and character generating signals areapplied to modify the'current through the same deflection means. It hasbeen found that this arrangement is to be preferred, especially whencharacters of typesetting quality are to be generated. Thus, amplifiercircuit- 21 supplies the current through an electromagnetic coil 37controlling the vertical location of the beam, and in like manner, thehorizontal amplifier circuit 22 controls the current through theelectromagnetic coil 38 controlling the horizontal location of the beam.Both the vertical and horizontal amplifier are responsive to voltagessupplied by the control circuit 35 and the character generator circuit20. Thus, the character positioning signals position the beam to locatethe character horizOntally and vertically on the face of the cathode-raytube while the character generating signals actually develop thecharacter on the face of the cathode-ray tube. When used in aphototypesetting operation, the image of the characters so formed arerecorded by photographic materials such as film or paper.

In a typesetting system the characters developed on the face of thecathode-ray tube 25 in H6. 1 will have different widths. The letter a,for example, may be assigned a width value of Wu, while the letter i hasa width value of Wi and the letter m has a width value of Wm. Each ofthese width values will depend upon the type and style of the font beinggenerated, but

normally characters such as those illustrated in FIG. 1 will bepositioned automatically after the preceding character has beengenerated by relocating the cathode-ray tube beam, the distance which itmoves being determined by the width of the previously formed character.With the type of character generator described herein, each of thecharacters stored on the character memory 10 has a width code associatedtherewith, and this width code is multiplied by the horizontal pointsize of the character to be generated, as determined by a signal fromthe control record 27. This multiplication occurs in the control circuit35, and the horizontal character positioning signal is modified toreposition the cathode-ray tube beam after the character generation hasbeen completed.

Referring now to FIG. 2, the character memory 10 includes a pair ofclock tracks 40 and 41, an several character tracks 42. In FIG. 3, theportion of the character memory 10 includ-

1. Apparatus for providing a graphical configuration by sequentiallydirecting a radiant energy beam to preset image positions to form adesired pattern of images on a radiant energy responsive surface todefine a said configuration, and comprising: means for sequentiallysupplying a plurality of sets of beam direction command signals witheach said set providing only the direction for the beam to proceed fromone image position the next of said preset image positions along eithera path parallel to one of first and second mutually perpendicularcoordinate axes or askew therefrom; deflection control means forsequentially deflecting said beam in accordance with said commandsignals from one said image position to the next said image position sothat for each directional command said beam is positioned so thatadjacent image positions are spaced by predetermined increments alongpaths respectively parallel to said axes, and beam control means forunblanking said beam only at each of said preset image positions. 2.Apparatus as set forth in claim 1, wherein said deflection control meansincludes circuit means for varying the incremental spacing betweenadjacent image positions along paths parallel to at least one of saidaxes.
 3. Apparatus as set forth in claim 1, wherein said sets of beamdirection command signals are coded signals, each set beingrepresentative of a specific beam direction and said defection controlmeans includes direction command signal decoding means for decoding eachset of coded command signals and providing therefor either a firstcoordinate signal representative of commanded directional movement alonga path parallel to said first coordinate axis or a second coordinatesignal representative of commanded directional movement along a pathparalleL to said second coordinate axis or both said first and secondcoordinate signals representative of commanded directional movementalong a path askew from said axes.
 4. Apparatus as set forth in claim 3,wherein said first and second coordinate signals are each eitherpositive or negative signals representative of the relative directionalong said axes, and first and second reversible counter means forrespectively receiving said first and second coordinate signals andproviding first and second count signals respectively indicating thecommanded first and second coordinate axis position of the imageposition corresponding to the commanded directional movement. 5.Apparatus as set forth in claim 4, wherein said first and second countsignals are digital signals, first and second digital to analog meansfor respectively receiving said first and second count signals andproviding firs and second analog deflection signals for incrementallydeflecting said beam for each said set of directional command signals.6. Apparatus as set forth in claim 5, including means for varying themagnitude of said first and second analog deflection signals dependentupon the location of said beam on said beam on said beam responsivesurface to compensate for nonlinear beam responsive characteristics sothat said incremental spacing along each of said axes is maintainedrelatively constant as configurations are formed at different locationson said surface.
 7. Apparatus as set forth in claim 4, wherein a saidconfiguration is formed in sections with each section defined by aplurality of said images and wherein said sequentially supplying meansprovides said plurality of sets of beam direction command signals forone section at a time and provides for the commencement of each sectiona coded pattern of section starting signals.
 8. Apparatus as set forthin claim 7, wherein said sequentially supplying means also provides adistinctive signal representative of the number of said sectionsrequired for each configuration, and counting means for counting thenumber of sections formed on said surface to insure that the correctnumber of sections are formed.
 9. Apparatus as set forth in claim 1,including means for positioning said beam along one of said axes priorto providing the next configuration on said surface, accumulator meanseffective to control the output from said configuration positioncontrolling means to establish the location at which the entireconfiguration will be formed; and means to update said accumulator meansafter each said configuration is formed so that said positioning meansrepositions said beam dependent at least in part on the width widthalong said one axis of the last said configuration formed on saidsurface.
 10. Apparatus as set forth in claim 1, wherein said surface isthe display surface of a cathode-ray tube and said beam is said tube''sbeam and said deflection control means includes: first circuit means forrespectively effecting positioning of said beam to major positions alongone of said coordinate axes at which desired configurations are to beformed and in accordance with beam position command signals; and secondcircuit means for effecting additional positioning of said beam alongsaid axis in dependence upon the selected major position of said beam tocompensate for nonlinear beam response characteristics of saidcathode-ray tube.
 11. The method of forming a graphical configuration ona radiant energy beam responsive surface by directing the beam in apredetermined sequence to preset image positions, and comprising thesteps of: sequentially providing a plurality of coded beam directioncommand signals each providing only directional information fordisplacing said beam to proceed from one image position to the nextimage position along either a path parallel to one of first and secondmutually perpendicular coordinate axes or askew therefrom; decoding eachof said command signals to obtain either a first coordinatE signalrepresentative of commanded directional movement along a path parallelto said first coordinate axis of a second coordinate signalrepresentative of commanded directional movement along a path parallelto said second coordinate axis or both said first and second coordinatesignals representative of commanded directional movement along a pathaskew from said axes; displacing said beam for each said codeddirectional signal in accordance with the decoded first and/or secondcoordinate signals so that said beam is positioned to the next presetimage position with the distances between adjacent image positions beingconstant along paths parallel to said respective axes; and unblankingsaid beam only at each said image position to thereby form the desiredgraphical image.